Elevator safety device.



.W. C. STRANG.

ELEVATOR SAFETY DEVICE.

APPLICATION FILED 050.4, 1912.

Patentd June 8, 1915.

3 SHEETS-SHEET 1- 5 woe wtoz 12 i 13442 was THE NORRIS PETERS CO4. PHDTD LITHOH WASHINGTON, Dv C.

W. C. STRANG.

ELEVATOR SAFETY DEVICE. APPLICATION FILED 050.4. 1912.

Patented June 8, 1915.

3 SHEETS-SHEET 2.

W HW" N WWW I 77% c 95mg THE NORRIS PETERS C0. PHDTO-LITHO.. WASHINGTON, D. (.1

W. C. STRANG.

ELEVATOR SAFETY DEVICE.

APPLICATION man 050.4. 1912.

1,141,986. Patented June 8,1915.

3 SHEETS-SHEET 3.

THE NORRIS PETERS 60., FHOTO-LITHO.. WASHINGTON, u.

ANTED sira rss rarest cri ics.

WALTER C. STRANG, OF YONKEBS, NEW YORK.

' i i ELEVATOR SAFETY DEVICE.

Application filed December 4, 1912.

To all whom it may concern Be it known that I, WALTER C. STRANG,

a citizen of the United States, residing in Yonkers, in the county of /Vestchester and State of New York, have invented a new and useful Improvement in Elevator Safety Devices, of which the following is a specift cation.

This invention relates to improvements in elevator safety devices, and has for an object the provision of simple, practical and efficient means for braking an elevator car in the event of its falling or attaining excessive speed.

Another object is the provision of a device for operating the clamp jaws of an elevator safety with a power depending upon the load.

A further object of the invention is the provision of a clamp jaw safety device which shall act with gradually increasing power through frictional operating mechanism and thereafter be operated by positive driving mechanism.

Other objects of the invention will appear hereinafter, the novel combinations of elements being pointed out in the appended claims.

On the accompanying drawings, Figure 1 represents an elevator system containing an I embodiment of my invention; Fig. 2 is a detail view in part section of the safety device; Fig. 3 is a sectional plan view of a pair of clamp jaws and the operatingwedge; Fig. 4-. is a sectional view of Fig. 2 taken on the line a-a; Fig. 5 is a sectional view of Fig. 2 taken on the line bb; Fig. 6 is a sectional view of Fig. 2 taken on the line cc; Fig. 7 is a detail view showing the resetting mechanism; Fig. 8 is a fragmentary end view of Fig. 7.

Like reference characters are used in denoting similar parts in all of the figures.

The well-known clamp jaw safety device has proved itself in many ways far superior to all other known devices for stopping an elevator car in times of emergency, such for instance as the parting of the suspension cables or excessive speed. In this device, the clamps are movedup into engagement with the guide rails with a predetermined maximum pressure which is always the same regardless of the speed and load of the car, The predetermined pressure of the clamp jaws on the guide rails must be sufiicient to stop a car with a maximum load Without dis- Speeification of Letters Patent.

Patented June 8, 1915.

Serial No. 734,827.

comfort to the passengers and without overstraining the elevator mechanism. It will be seen, however, that with the safety device so adjusted as to take care of a maximum load in a satisfactory manner, when the car is lightly loaded, the action of the safety device is much too powerful and tends severely to shock and jar the passengers and elevator mechanism. It is to obviate this defect that the present invention is particularly designed.

Referring to Fig. 1 of the drawings, C designates an elevator car which may be suspended from the cables D and operated by means of any suitable power driven mechanism such as a hydraulic, electric or steam motor in the usual way. A governor.

cable G is arranged to run with the car, being driven therefrom by means of the releasing carrier H. The cable G drives a governor E arranged at the top of the hatchway and maintained under tension by a weighted tensioning device I. A safety cableJ is securely attached to the governor cable G and after passing over the safety drum K a number of times is secured thereto. The governor controls a pair of cable clamps F arranged to grip the governor cable G toeifect the actuation of the safety drum K in the event of excessive car speed.

In Figs. 2 and 8 are shown the usual left and right threaded shafts 1 and 2, each of which is connected to a wedge such as 8, adapted to move apart thelevers a and 5, and thereby apply the clamp jaws to opposite sides of the guide rail 6. The safety drum K is rotatably mounted upon a sleeve 9 which is screw threaded onto the shafts 1 and 2, the latter being supported and guided in suitable brackets 7 and 8 secured to the safety plank or bottom of the car. The left hand end of the sleeve is flanged so as to enter a recess in the bracket 7 and is held against endwise movement by a plate 10. The driving connection between the drum and sleeve comprises a series of disks such as 20, 21, 22 and 23, which are carried on the sleeve, but may rotate with respect thereto. Other disks such as 24, 2 5, 26, 27 and 28 are interspaced between the disks 20, 21, 22 and 23 and are arranged to rotate with the sleeve. Any desired number of disks may be used and the same may be punched out of sheet steel similar to those used in multiple disk vehicle clutches. The driving connection between the disks 24: 25, 26, 27 and 28,

and the sleeve 9, is formed by a plurality of detents such as 30, which enter corre spon'ding slots or keyways milled in the sleeve in the direction of its axis. The disks 20, 21, 22 and 23, are formed of, similar blanks having portions varying in extent cut away, from their circumferences, that is to say, the disk 20 has a notch or cut out portion lying between the edges 42 and 43, the disk 21 has a cut away portion bounded by the edges42 and 44, the disk 22 has a cut away portion bounded by the edges 42. and 45, and the disk 23 has a cutaway portion bounded by the edges 42 and 46,: the edges 42 of each disk,;lying in the same axial 7 plane, A detent 31 is formed on the inner surface of the drum and its function is to drive the disks 20, 21, 22, 23 and 28.- 'The last named disk is circular in form; and has a detent 32 upon its circumference. An adjustable spring 33-bears against one end of a yoked lever 34 which ispivoted atv 35to V the drumhead'14'and is provided with a pair of detents suchas 36, which bear upon thedisk 28 at" diagonally opposite points. A pair of eye bolts 37,v 37, are secured to the yoked lever 34 and. extend through the drumhead 14 and are united by a member car by a hand wheel 18 but. normally held out of mesh with thebevel gear teeth'16 by a 1 spring 19. f The operation of the mechanism justdescribed is as follows: Should the elevator car attain too great a speed, the governor operates the clamps'F (Fig.1)! to grasp'the governor cable and hold the same against movement. As soon as this takes place the continued movement of the car disengages the governor cable from the car at the releasing carrier H and the safety drum. K

begins to rotate throughfthe unwinding ofv v .the safety cable J.. The sleeve 9 will rotate at, the same speed as the drum being driven through the medium of the fri tiondisksall of which rotate as a unit, and the right and left screws will bequickly moved outwardly to apply the gripping jaws to the guide'rails.

As soon as the gripping'jaws are set up on the guides with a predetermined ,pressure, the rotation" of the sleeve meetswith resistance and the sleeve together with the disks tends to stop rotating. The continued rotation ofthe drum, however, 'moves the detent31' on. the drum against the edge 43' the sleeve increasesthe disk 20 slips between 3 the disks 24 and 25 and the detent 31 on the drum engages the edge 44 of the disk 21 whose frictional engagement with the disks 25 and 26 causes an additional torque to be transmitted from the drum to the sleeve and hence to the gripping jaws. In like manner the disks 22 and 23 are successively picked up by the detent 31' andthe torque of the sleeve correspondingly increased. If. the gripping power of the jaws is insufficient at this time to stopthe car, a further rotation of the drum carries the detent 31 againstthe detent 32 of the disk 28, andsince this disk is keyed into the sleeve, it follows that a direct and positive driving engagement is effected between the drum and sleeve and the screw threaded shafts 1 and 2'are moved outwardly with a power which is only limited by the power of the governor clamps F and the tensile strength of thegovernor and safety cables G1 and J, respectively, which is ample to stop the .car with any loadit may ever be called upon to handle. The spring 33 determines in part the frictional driving power of the disks and. since this spring is adjustable,'any desired torqueof the sleeve maybe obtained through thesetion of the friction disks alone.

From the foregoing description it will be seen that the rail gripping jaws are immediately actuated upon the tripping ofthe safety governor. As soon as, the jaws meet with resistance the action of the. friction disks gradually increases the gripping powerof the jaws until finally the jaws are positively driven from the safety drum and. their'power becomes a maximum. If the'elevator car be lightly loaded, the power of the safety device when actuated through the. friction disks alone is sufiicient to smoothly and gradually stop the car. If the car be very heavily loaded it may be that the friction disksalone would merely retard the car without completely stopping it, in which case the positive driving means 7 comes into play and the car is stopped with certainty- Even though the friction driving mechanism. should become disarranged by the breaking of the spring 33 or from other causes, the safety device is still operable to stop the car and is by no means disabled.

As before. pointed out the drumis preferably made fluid. tight and it is intended that the, same be filled with oil so as to sub merge all of the working parts. This feature is particularly desirableinconnection with an elevator safety device, since the same is seldom called into use and very often only after long periods of disuse and it has been found that long periods of disuse tend to rust the parts and render their operation very uncertain, which is most undesirable. The oil not only acts as a lubricant, but also keeps the parts from deteriorating, no matter how long they may stand idle.

In order to reset the safety device after the same has been operated, the attendant in the car moves the lever 41 in a direction to overcome the spring 83, and relieve all lateral pressure from the friction disks- The hand wheel 18 is now depressed so as to bring the bevel gear 17 into mesh with the gear teeth 16 on the drum, and the latter may then be rotated backward, which in turn will drive the sleeve 9 through disk 28 in a direction to release the gripping jaws from the rails. Owing to the form of the various friction disks, the latter will assume their proper relative positions as shown in the drawings with the edges 42 of each disk in axial alinement.

The improved safety device herein set forthcontains all of the advantages of the well known clamp-j aw safety with the added features of providing a bath of oil for the principal working parts, and the combined frictional and positive driving or actuating mechanism. I Since the frictional driving mechanism alone may be depended.

upon properly to stop a lightly loaded'car,

the same mechanism augmented if neces sary by the positive driving or actuating mechanism will effect an equally smooth stop of a heavily loaded car, the braking power for all loads being automatically proportioned to suit any particular load so as to stop the car in as short a space as possible consistent with smoothness of operation and without any possibility of shocks or jars or discomfort to the passengers, regardless of all load and speed conditions.

I desire not to. be limited to the precise construction and arrangement of parts herein set forth, since it is obvious that one skilled in the art could readily make various changes therein without departing from the spirit and scope of my invention.

What I claim and desire to have secured by Letters Patent of the United States is 1. In an elevator safety device, the combination with rail-gripping clamp-jaws, of actuating mechanism, friction disks interposed between said actuating mechanism and said clamp jaws, and means to effect the successive operation of said disks.

2. In an elevator safety device, the combination of rail clamps, a rotatable safety drum for actuating said clamps, intermediate mechanism comprising a plurality of friction disks for transmitting motion from the drum to the said clamps, and automatic means to effect the successive operation of said disks. I

3. In an elevator safety device, the combination of rail clamps, right and left screws for actuating saidclamps, a safety drum, and friction mechanism for transmitting motion of the drum to the same with increasing power.

34:. In an elevator safety device, the combination of rail clamps, right and left screws for actuating said clamps, a safety drum, and a multiple disk friction mechanism for transmitting cumulative power from the drum to the screws.

5. In an elevator safety device, the com-v bination of rail clamps, right and left screws for actuating said clamps, a safety drum, and frictional and positive driving mechanism interposed between the drum and actuating screws. 7

.6. In an elevator safety device, the combination of rail clamps, right and leftscrews for actuating said clamps, a safety drum, and a multiple disk. friction and positive driving mechanism interposed between the drum and actuating screws.

7 In an elevator safety device, the combination of rail clamps, right and left screws for actuating said clamps, a sleeve threaded onto said screws, a safety drum, and means comprising a plurality of friction disks for transmitting motion from the drum to the sleeve with cumulative power to effect the actuation of therail clamps.

. 8. In an elevator safety device, the combination of rail clamps, right and. left screws for actuating said clamps, a sleeve threaded onto said screws, a safety drum, and frictional and positive driving mechanism operatively connecting said drum and sleeve.

9. In an elevator safety device, the combination of rail clamps, right and left screws for actuating said clamps, a safety drum, and a friction transmission mechanism forming a driving connection of automatically varying powerbetween the said drum andolamp actuating mechanism.

10. In an elevator safety device, the combination of rail clamps, right and left screws for actuating the said clamps, a safety drum, and a friction transmission mechanism adapted to transmit motion from the said drum to the screws with automatically varying power.

11. In an elevator safety device, the combination of rail clamps, right and left screws for actuating the clamps, friction mechanism for operating the screws, and means for automatically varying the power of said friction mechanism.

12. In an elevator safety device, the combination of rail clamps, right and left screws for actuating the clamps, friction mechanism for operatin driving power of said: friction mechanism,

13. In an elevator safety device, the com-- bination of rail clamps, right and left screws for actuating the said clamps, a

sleeve threaded on't-hescrews', a safety drum,

means'ffor transmitting motion fromv thev drum to the sleeve through a variable power friction transmission mechanism, and. a positive driving connection between the said drum and sleeve.

14. In an elevator safety device, the combination of mucl amps, right and left screws for actuating said clamps, a sleeve threaded on the screws, a safety drum, and

means for transmitting motion from the drum to the sleeve: with a power which increases as the drum rotates 15. In an elevatorsafety device,the combination of rail clamps, right and left screws for actuating said clamps, a sl'eeve threaded on the screws, a safety drum, and yielding means for transmitting motion from the drum to the sleeve with a power which increases as the drum rotates.

copies of this patent may be obtained tor 16. In an elevator safety device, the com bination of rail clamps, screws for actuating said clamps, a sleeve threaded on said screws, a safety drum, friction transmission mechanism between the said drum and sleeve, automatic means for varying the power of said friction mechanism and means for maintaining said friction transmission mechanism in a bath of oil.

17. In an elevator safety device, the combination of rail clamps, screwsfor actuating said clamps, a multiple disk driving connection for operating the screws, automatic means for varying the power of said driving connection, a safety drum connected to and surrounding the said driving connection, and meansfor retaining a supply of oil in the drum.

18. In an elevator safety device, the combination of a car, rail clamps onthe car,

the screws, 'and means for automatically increasing the screws for actuating said clamps, a safety drum, a multiple disk friction driving connection between the said drum and screws, a springv for maintaining" pressure throughout the disks, and means on the car for re-.

lieving the saidv pressure and for rotating the drum,

19. In an elevator safety device, the combination ofrail clamps, screws for actuating said clamps, a safety drum, a plurality of frictiorr disks. forming a yielding driving' connection between the said screws and drum, and means for effecting the successive actuation of said disks and thereby actuatthe initial operation o'f the said clamps by means of the frictional connection al'one and thereafter by means of the: positive driving connection; 7

22. In an elevator and positive driving connection hetweenthe drum and clamps-, 'and means for effecting the initial operation ofthe said' clamps through the yieldable driving connection safety device, the combination of rail clamps, a safety drum arranged to actuate saidclamps, a yieldablewith gradually increasing torque and thereafter by means of the p nection. I

In testimony whereof, I have signed my name to this specification in the presence of two subscribing witnesses;

, V WALTERC. STRANG. Witnesses: v s

w. n. BRAnr, JAMES G; BETHELL;

fivecents each by'addfessing Commissioner of Patents, Washington, 1); up v a J ositive driving ;con-- 

